I drove my car for the last time yesterday morning (Sunday 11/19/2023)...

[JPuehl]

... with it's current PS2 turbo. Starting the swap to a PS750 and so looking forward to it. I feel the PS2 was getting boring and maxed out so time for something new to keep me entertained for a while, lol. (Ignore the oil on the mat under the front of the car, I keep forgetting to wipe that off but it is a BMW so I don't really need to explain what that is, lol).

 

[wheela]

That thread title is a little disconcerting, lol! Looking forward to hearing how everything goes Are you gonna take any ps2 vs ps750 comparison pics for us?

 

[JPuehl]

That thread title is a little disconcerting, lol! Looking forward to hearing how everything goes Are you gonna take any ps2 vs ps750 comparison pics for us?

LOL, I thought the title might catch a few by surprise. I can take all the pix people want, I have my original factory turbo still so I can take pix of stock, PS2 and PS750.

 

[mwpa71]

Good luck with it Jimmy.
Ps is the wg flap welded on?

 

[JPuehl]

Good luck with it Jimmy.
Ps is the wg flap welded on?

"Welded on" at what point? In the pic you can see the flap is welded to the arm and the arm on the outside is welded to the shaft.

 

[mwpa71]

"Welded on" at what point? In the pic you can see the flap is welded to the arm and the arm on the outside is welded to the shaft.

Cheers.thanks for confirming, I thought it was looking at pic..
There was a failure of a flap falling off..some flaps are peened on as opposed to welded. Can make for a weak joint..there was a mention of this way way back. Not sure if any early deliveries had "peened" flaps.

 

[JPuehl]

Was going to start a thread on the tuning progress of the PS750 but had forgotten I started a thread on my swap, so I'll just add to it here. Now that we gotten past the "phantom misfire" issue above ~5500 rpm and more recently the 3 bar relative boost limit, I've been able to work on actually tuning this thing. This past weekend was the first time since completing the swap that I've been able to get actual logs. I got 1 good log and a bunch of crappy ones because I think my spark plug gap is too big, they're at .022" and should be closer to .018" for 28# of boost. I ordered new plugs and am waiting for those to arrive and some more spring weather so I can log again, lol.

I also got a 100-200 kpm, and while I didn't get a flying start, I went WOT at 96 KPH in 4th, I still managed 5.73 seconds. Hopefully with a flying start in 3rd and a bit more tuning I can get more from it.

This is the log with MPH and KPH manually added.

20240316 - rev 15.2 - 1

www.spoolstreet.com

 

[JPuehl]

Alright, so today is dyno day. I have an appt for a dyno session at 11:00 PT and hopefully I'll be driving the car home, lol. I've had 2 people predict 620+ rwhp, I'm hoping for anything above 600. The temp is supposed to be ~55* during the session but the humidity 91% right now, down from 93% at 5:00 am. I'll check the temp, and DA (using the Dragy) when I get to the shop.

This is a street log for the tune I'll bet dynoing, I have a few variations of this tune to test as well. I'll report back when I'm done.

20240411 - dyno base tune (test) - 1 - 5th gear pull

www.spoolstreet.com

I am purposely ramping up the boost target because this PS750 turbo spool really freakin quick and I don't want to be at 28# boost in 900 rpm after going WOT at 2500 rpm, lol.

 

[JPuehl]

The car survived the dyno session! I'm happy with the results but a little disappointed it didn't make more power, it made 618 rwhp (my goal was anything over 600).

Here's the conditions according to Dragy:

And here's the fuel I used:

And here's the dyno sheet for the best pull:

 

[JPuehl]

Getting quicker.

 

[wheela]

The car survived the dyno session! I'm happy with the results but a little disappointed it didn't make more power, it made 618 rwhp (my goal was anything over 600).

Here's the conditions according to Dragy:
View attachment 93130

And here's the fuel I used:
View attachment 93131

And here's the dyno sheet for the best pull:
View attachment 93132

Just noticed this dyno graph shows you ran her out to 7600rpm? Is this a mistake, or have you increased your redline?

 

[wheela]

Getting quicker.

View attachment 93260

Go n55e

 

[JPuehl]

Just noticed this dyno graph shows you ran her out to 7600rpm? Is this a mistake, or have you increased your redline?

The RPMs are based on the rollers, so it most likely shifted into 6th for a bit. In my logs it was only ~7k in 5th then shifted.

 

[JPuehl]

Just noticed this dyno graph shows you ran her out to 7600rpm? Is this a mistake, or have you increased your redline?

And speaking about RPMs, when I dyno'd my car with the PS2, peak HP was 511 @ 23# @ 5950 RPM. With the new exhaust manifold the PS750 has, peak HP was at 6600 RPM, so about an additional 650 usable RPM. Not to bad.

 

[wheela]

And speaking about RPMs, when I dyno'd my car with the PS2, peak HP was 511 @ 23# @ 5950 RPM. With the new exhaust manifold the PS750 has, peak HP was at 6600 RPM, so about an additional 650 usable RPM. Not to bad.

@JPuehl You're getting some press over on the M2 forum

BMW n55 new pure turbos (pure 500 and pure 750)

BMW n55 new pure turbos (pure 500 and pure 750)

f87.bimmerpost.com

 

[wheela]

I saw a note about your exhaust over there, sounds interesting. Do you have any pictures of it?

 

[JPuehl]

@JPuehl You're getting some press over on the M2 forum

BMW n55 new pure turbos (pure 500 and pure 750)

BMW n55 new pure turbos (pure 500 and pure 750)

f87.bimmerpost.com

Thanks for pointing out!

 

[JPuehl]

I saw a note about your exhaust over there, sounds interesting. Do you have any pictures of it?

I do have pix of the exhaust that I'll post up in a few minutes and a video of the sound from the back during a dyno pull I'll also link.

 

[JPuehl]

Here's some details and pix of my current exhaust, which is the modified BMR 3.5" exhaust for a 135i.

Here's a link to a video os the exhaust during a dyno pull:

In this pic, the exhaust on the left was the 1M style that came on my car when I bought it. The exhaust on the right is the BMR 3.5" that was on my previous 135i.

This is how the tips of the BMR exhaust lined up with the factory 1M bumper. The reason for the damage to the left tip is the wrecking yard forklift driver when they moved my previous 135i around.

After careful measuring, below are pix of how I modified the tail section of the exhaust.

And here's the (almost) finished product. I want to go with a split tip but am having a hard time finding a 3.5" inlet and dual 2.5" outlet tip.

 

[wheela]

Wow, that thing sounds awesome! Is it pretty loud just cruising around town?

That 1m style exhaust that was on your car, was the battery relocated, or any physical mods done to get the passenger side outlet to fit?

In addition to going to a split tip, do you think you'll add a second fork back on the passenger side?